In BGE, how do I move an object up with a motion actuator for a few seconds then bring the object back to its original area
I suggest to play an action that lifts the object. 

A simple logic would be to have one sensor that measures when to block (e.g. keyboad sensor on E).



Activate an action actuator that plays the action in flipper mode. This means when the blocking request ends -> the action will be played reverse.